As shown in FIG. 1, a prior art fast joint is composed of a main body 1, a sleeve 2, a rotary body 3, and a spring 4. The main body 1 is provided with a channel 11 and three guide grooves 12 located in the wall of the main body 1 such that the guide grooves 12 are in communication with the channel 11. The main body 1 is further provided with a stopping ring 14 located under the guide grooves 12, an outer threaded portion 15 located under the stopping ring 14, and a connection portion 16 extending from the outer threaded portion 15. The spring 4 is fitted over the main body 1 such that one end of the spring 4 is located in the channel 11. The sleeve 2 is engaged with the main body 1 such that the sleeve 2 is stopped by a protruded edge 17 and the stopping ring 14 of the main body 1. The sleeve 2 is provided in the inner wall thereof with a rib 21 corresponding in location to an elastic piece 13. The rotary body 3 is provided with a female threaded portion 31 which is engaged with the male threaded portion 15 of the main body 1. The rotary body 3 is provided in the bottom end thereof with an opening 32.
Such a prior art fast joint as described above is defective in design in that the main body, the sleeve, the spring and the rotary body must be made separately by the separate molding tools, thereby resulting in a substantial increase in the cost of producing the prior art fast joint. In addition, it is difficult to carry out an effective quality control of the component parts of the prior art fast joint. Moreover, the component parts, such as the spring, of the prior art fast joint are vulnerable to wear or fatigue, thereby undermining the function of the prior art fast joint.